Found a set for sale would rather not get new rims if not needed will i have to et wheel spacers if so might be worth getting some steal rims cheep

If your factory wheels are 16x8" then 305/70R16 tires will mount up to the wheel just fine. As far as fitment on your Jeep, we'll definitely need to know your wheels backspacing / offset, but generally speaking 305s are probably going to be too wide (rubbing) for your '99 TJ.